Copper-base alloy



United States Patent "ice The present application is:a.,continuation-in-part of my application. Serial No. 290,070, filedMay 26, 1952, now-abandoned,for copper-base alloys and the productionthereof and. relatingto alloys in which copper is. the preponderantelement and which contain nickel and Zinc.

My invention is essentially concerned with improving alloys consisting;of nickel from 4.0 to 22.5%, zinc'from.

4.0 to less than 20.0% and copper, the quantity of nickel not exceedingtwice the quantity ofzinc and preferably being not less than V5 and notmore than of the quantity of zinc. These alloys are hereinafter referredto as the basic-alloys. The p ercentages of the alloying elements hereinand in the claims are stated by reference to weight.

I have found that the addition of cadmium above a certain minimumquantity an'dwithin certain proportions not only enables corrosionresistance to be improved but also enables. high hardness, tensile;strength and elongation values to be obtained with the, requisitemechanical working and annealing, but that "some of suchyalloys willrespond satisfactorily to subsequent heatv treatment or treatments andto further, mechanical Working still further to increase the hardnessand tensile, strength without iindue'red'uction of: the elongationvalue.

It has been proposed to add aluminium to coppernickel-zinc alloys, e.. gU. S. patent specification No. 2,101,625fin an amountfrom 0.5% to3.0%;to increase hardness, but this increase isstatedto be obtained onlywhen nickel and' aluminium are present together in the alloy.

The hardening efiect, of aluminium. is again mentioned in U. "S; patentspecification No. 2,101,930 when the aluminium i'sipresentfrom 05% to3;0% together with nickel, and the patentee stating. that if thealuminium is omitted, little or no hardnessis obtained by heattreatmentat low temperatures (heating for two hours at a temperature of 450 C. isreferred to). In this specificati'on it has been proposed to add cadmiumfrom 0.05%

to 3.0%,,primarily to enhance corrosion resistance, the

amount employed in each example being 0.5%.

The improved alloys according to my invention are substantially. freefrom aluminium which has deleterious effects onth'e aforesaidibasicalloys leading for example to hot-shortness in the case. of hot rollingthe alloys, and to striations in cold rolling and polishing due. toparticles of aluminium having failed to go into solution, segregated at'the.grain boundaries, and also being present in the/form of abrasivealuminium oxide and rendering'the alloys proneto brittleness-andinter-crystalline failure.

I have fotind"thati'in"the'absence of aluminium the addition of cadmiumto the said basic alloys has the propertyf'of itself causing greatlyi'mprovedtensile strength and hardness/at least comparable to thoseobtained by the aluminium-containing alloys. Moreover, the addition'ofcadmium to atleast some of the said basic'alloys renders thealloysfreadily responsive to heat treatment at low temperatures-afterbeing mechanically worked,

2,849,310 Patented Aug. 2 5

2.. e. g., rolled, and in some casesnwillcause,increased harm ness ofthe alloys whentreated attemperatures as low as 100 C. and I have insome case s even obtained optimum resultsas to hardness when thetemperature is as low as 250 C. to .30 0 C. Moreover I have ob-,tainedtheincreased hardnesses with heat treatments of as little aduration ashalf anhour.

To the foregoing ends, improved alloys according to the p resentinvention are substantially free from aluminium and comprise not lessthan 4.0% or more than,

22.5% nickelpnot less .th an 4.0% to less,than 20%,zinc,

not. lessthan andf'preferably morethan 0.5% and not more than 3.5% ofcadmium and not less than 55 P rc ntof opp r, e quant ty ni k l in p frably, not less than Ms andnot morejthan, Vt, of the quantity of' .zinc, and, inany event, not exceeding twice the quantity of"zi nc.Themechanical properties, e., g,, ductility maybe further improved bythe addition of iron from 0.01 to 21.50 percent.

oys o ng to y nvent mhtw s. a ch s colour and lnstre andwith atextureenabling them to take a high.polis li consist ofcopper andthefollowing additional metals, viz.,

Percent Nickel 6.00 Zin v 5- Cadmium 1.75

Iron 0.20

The colour varies according to the composition and alloys with apleasing silver-like colour and lustre and of a, texture enabling themto take a high polish are produced and high corrosion resistanceobtained by employing nickel and Zinc in the higher amounts in themaximum ranges herebefore mentioned, i. e., alloys consisting of copperand the following additional metals:

Range 2 Percent Nickel 15.00 to 22.50

Zinc 15.00 to 19.75

Cadmium- 0.75 to 2.75

with or-without Iron 0.01 to 1.00

One alloy (hereinafter called alloy B) within the limits justreferred toconsists of copper and the following additional metals:

Percent Nickel 17.45 Zinc 19.00 Cadmium 2.25 Iron 0.30

The improved alloys may be produced free from inclusions, blowholes andother faults by ordinary known melting or casting methods, and inmelting practice particularly during pouring it is desirable to avoidundue air currents in the neighbourhood of the molten metal.

The alloysafter-casting maybe mechanically worked, e. g-,, rolled in thecase 'of sheet material until the required gauge is reached. The alloysmay also be extruded through dies. Annealing maybe done -after eachworking in the usual manner at the customary temperature for the presenttypeof alloy, e. g., in the range of from 550 C. to 880 C., the alloybeing air-cooled from this temperature, but quenching has also provedsatisfactory with some of the alloys. A

The improved alloys can be produced in the form of sheet, strip, tube,pipe, wire, bar, rod, or other forms and a great variety of articles maybe formed or machined therefrom, e. g., by cold or hot drawing andstamping, pressing, forging, cutting, piercing, drilling and turning.Many of the said alloys are capable of taking spring temper and can besoldered, brazed or welded.

Some of the improved alloys are responsive and may be subjected to heattreatment at low temperatures to increase the hardness and tensilestrength, and this heat treatment may be followed by mechanical workingstill further to increase these values.

Comparative tests have been made between alloy A" and a tri-partitealloy consisting of 88 percent copper,

6 percent nickel and 6 percent zinc (hereinafter termed e alloy Z) whichhas a gold colour and good lustre. Alloy Z" can be mechanically workedand annealed at a temperature from 450 C. to 750 C. and when reduced bymechanical working, e. g., rolling, hardens and acquires good tensilestrength and elongation values.

These tests showed that alloy A in the fully annealed condition had atensile strength of 20-24 tons per sq. inch, a diamond point hardness of75 to 80, and an elongation of 50-60 percent in 2 inches, whereas thecorresponding figures for alloy Z were: tensile strength 15-18 tons persq. inch, a diamond point hardness of 62 to 70 and an elongation of45-50 percent in Z-inches. Alloy A was rolled by the customary methodsto a tensile strength of 45 tons per sq. inch and a diamond pointhardness of 220-235 whereas the corresponding figures for alloy Z were32-36 tons per square inch and 125-135 diamond point hardness. At suchtensile strengths and hardnesses alloy A had an elongation of 15-20% intwo inches whereas alloy Z had an elongation of 7-10% in two inches.

Further examples of alloys (C, D, E and F) within the range 2 accordingto the invention and which are particularly useful are constitutedapproximately as follows:

C D E F Percent Percent Percent Percent 58. 50 64. 80 58. 50 64. 20. 1015. 70 21. 16. 20 19. 50 18.00 19.00 18.00 1. 50 1. 20 0. 95 1.80 0.300. 3O 0. Nil

The alloys C, D, E and F when reduced by rolling to the percentagesshown without intermediate annealing, had the results in diamond pointhardnesses set out in the table below:

A feature of the invention consists in giving the alloys aheat-hardening treatment at a temperature up to 500 C. preferablyfollowing reduction, e. g., rolling. This heat treatment may be followedby further reduction, e. g., rolling, if desired,

I have found that heat hardening is particularly effective in relationto alloys wherein the nickel lies between 15% and 22.50% with the coppercontent not exceeding 70% and the addition of cadmium kept to the limitsof 0.75% to 2.0%, zinc making up the remainder with or without theaddition of iron, the latter preferably not exceeding 0.30%. In theseheat hardening ranges good ductility has also been obtained.

Specimens of alloy C (hereinafter termed C and C were taken at 90% and40% reduction, of alloy D at reduction, alloy E at reduction and alloy Fat 70% reduction and subjected to such heat treatment with the resultsin diamond point hardness as shown in the table set out below:

Temperatures, O. Alloy Allo Alloy Alloy Alloy C1 C27! D E HF" Note-Allheat treatment times were of half an hour duration. 1 No reading taken.

Tensile strengths increased correspondingly with the hardness resultsand ultimate tensile strengths of over 60 tons per sq. inch wererecorded.

Considerable springiness was achieved, and bending tests proved that thealloys respond well, bending through without cracking.

Each of the heat operations hereinbefore described were followed by aircooling but I found quenching, e. g., water quenching, after annealingin certain cases, e. g., alloys D and E, to be satisfactory.

Improved elongation and ductility was observed when the alloys wererolled to full hardnesses with intermediate annealing in place of thereduction by rolling without this method as was carried out for thetests shown in the tables.

By the expression an alloy'consisting essentially of in the claimingclauses hereof, I mean an alloy which contains the elements expresslytherein mentioned in the expressly mentioned amounts and withoutaluminium save for unavoidable traces, but which may also contain atleast one optional element added for those purposes described inmetallurgical publications, e. g., up to 10 percent of cobalt to promotestrength at high temperature, up to 7.5 percent of lead to promotemachineability, up to 5.0 percent of chromium to promote wearresistance, up to 5 .0 percent of rhodium to promote water repellance,and up to 3.0 percent of silicon, manganese, titanium, vanadium,beryllium or molybdenum to promote hardness or toughness, or of tantalumto promote resistance to chemical corrosion, or of tellurium forfacilitating machiming, or of zirconium to promote electricalconductivity, provided that the total of all these optional metals doesnot exceed 12 /2 percent of the alloy, and that magnesium, phosphorus,and silver are absent (save for unavoidable traces) or magnesium andphosphorus if present are less than 0.25 percent and 0.1 percentrespectively, the addition of silver tending to reduce thesusceptibility of the alloys to hardening and furthermore to lessentheir corrosion resistance.

Whilst impurities of the unwanted elements in minute quantities cannotalways be avoided, these elements should not be added, and theirpresence even as impurities is undesirable. Moreover it is a feature ofthe invention that the results aimed at can be obtained by the presenceof the elements copper, nickel, zinc and cadmium (with or without iron)without any additional elements, as is shown in the examples herein, andthis is the form I prefer my improved alloys to take, since the fewerthe elements that are employed to obtain the desired results, the betterin general are the alloys.

What I claim is:

1. An alloy consisting essentially of from 4.0% to 22.5 of nickel, from4.0% to less than 20% of zinc, more than 0.5% and up to 3.5% of cadmiumand not less than 55% of copper, the quantity of nickel not exceedingtwice the quantity of Zinc.

2. An alloy consisting essentially of from 4.0% to 22.5 of nickel, from4.0% to less than 20% of zinc, more than 0.5% and up to 3.5% ofcadmium,from 0.01% to 2.5% of iron and not less than 55% of copper, the quantityof nickel not exceeding twice the quantity of zinc.

3. An alloy otherwise according to claim 1 save that the upper limit ofnickel is 8.0%; and of zinc is 8.0% and the lower and upper limits ofcadmium are respectively 1.25 and 2.25%.

4. An alloy otherwise according to claim 1 save that the lower limit ofnickel is 15.00%, of zinc is 15.00% and the lower and upper limits ofcadmium are respectively 0.75 and 2.00%.

5. An alloy consisting essentially of copper and 6.00% of nickel, 5.90%of zinc, 1.75% of cadmium and 0.20% of iron.

6. An alloy consisting essentially of copper and 6 17.45% of nickel,19.00% of zinc, 2.25% of cadmium, and 0.30% of iron.

7. An alloy consisting essentially of copper and 20.10% of nickel,19.50% of zinc, 1.50% of cadmium, and 0.30% of iron.

8. An alloy consisting essentially of copper and 15.70% of nickel,18.00% of zinc, 1.20% of cadmium and 0.30% of iron.

9. An alloy consisting essentially of copper and 21.25% of nickel,19.00% of zinc, 0.95% of cadmium and 0.30% of iron.

10. An alloy consisting; essentially of copper and. 16.20% of nickel,18.00% of zinc, and 1.80% of cadmium.

11. An alloy consisting essentially of from 4.0 to 22.5% of nickel, from4.0 to less than 20% of zinc, from 0.75 to 3% of cadmium and not lessthan of copper, the quantity of nickel not exceeding twice the quantityof zinc.

References Cited in the file of this patent UNITED STATES PATENTS2,075,509 Davis Mar. 30, 1927 2,101,930 Davis et al. Dec. 14, 19372,124,974 Hensel July 26, 1938 5,79 Hensel et a1. Jan. 31, 1939

1. AN ALLOY CONSISTING ESSENTIALLY OF FROM 4.0% TO 22.5% OF NICKEL, FROM4.0% TO LESS THAN 20% OF ZINC, MORE THAN 0.5% AND UP TO 3.5% OF CADMIUMAND NOT LESS THAN 55% OF COPPER, THE QUANTITY OF NICKEL NOT EXCEEDINGTWICE THE QUANTITY OF ZINC.